The Untamed Olive: An Introduction to Wild Olive Trees
A path runs past my house, angling up the steep slope between dry-wall terraces faced with granite and pink limestone, where grape vines climb trellises of wild chestnut branches bleached by the sun to the color of bone. On a map of the area drawn by French surveyors at the beginning of the nineteenth century, after Napoleon had pocketed Liguria during his conquest of Italy, it appears as an “ancient roadway.” It’s at least as old as the Middle Ages, and a local historian believes it dates to Roman times, perhaps even to the Iron Age. These days it’s only traveled by a few elderly farmers; the earth is soft underfoot between the uneven cobbles, and large stretches of its course are overgrown in summertime by clover and thyme and wild mint. Yet the landscape still respects this ancient route: the terraces defer to its straight, sharp vector, and the medieval farmhouses on either side face toward it like people around a campfire, glad for its company and movement and clatter of trade, its news from the wider world. The path was here before every other thing in this landscape, and everything is oriented to it. Everything except one. As the path crosses a saddle on the hillside a hundred meters above my house, a charmed spot where the sunlight lingers in the afternoons and spring violets bloom weeks earlier than in the valley below, it makes a small horseshoe bend, where centuries of travelers have taken five extra steps to avoid something in their way. This ancient obstacle is an olive tree, squat and thick-trunked like the local farmers, its partially exposed roots gripping the soil like a pair of old hands. The bark is pierced with holes made by woodworms, birds, nails, and what may have been bullets (during World War II, partisans sometimes hid from the Fascists and Nazis inside the hollow trunks of giant olive trees). Inside the trunk there’s a patch of charred wood from some wildfire beyond living memory, which must have devastated the tree. But in the fiercely patient way of olives, green shoots grew up from the charred remains and the tree was reborn. Like the mythic olive tree on the Acropolis cherished by the Athenians as the talisman of their city, which burned in the Persian sack of 480 BC but sprouted anew the next day from its smoking stump, a sign that the city would survive and prosper despite the disaster. Or like the olive tree at the head of the bay in Ithaca, which Odysseus sees when he finally returns there after his epic voyage, the one fixed point in a landscape altered by long absence, which tells him that he’s home. Until I moved here ten years ago, this detail made no sense to me: why would Homer have chosen an olive tree to make Odysseus realize he’s back in Ithaca, and not, say, the generous curve of the bay, or the familiar silhouette of the surrounding hills? Then I began to notice the olive tree on the hill behind my house as I returned each day from my own modest odysseys. Somehow it was that tree, and not the old stone path or the shape of the horizon or even the roofline of my house, that I looked for. It seemed natural to think of the tree in mythic terms. It has watched a procession of peasants, priests, Napoleonic soldiers and Renaissance mercenaries, highwaymen and barefoot saints walk down this roadway and vanish into the sandstorm of time. It seems as permanent a part of this landscape as the hillside itself, the pink limestone cliffs across the valley, or the bright blue ribbon of sea beyond them, where Corsica floats like a dream on clear mornings.
-Tom Mueller, Extra Virginity
Image (from aristoleo.com): Athan, the founder of Aristoleo resting on a 2,700 years old olive tree in Aigina Greece.
I am a bit of a romantic, but my guess is the picture Tom Mueller paints above — of the lone wild olive tree gripping the earth and never letting go while the aeons come and go — would move even the toughest individuals. It is the closest living thing we have to eternal life, to the untamed, primordial nature.
The story of olive trees is as long and varied as the history of humanity. Olive trees have shaped civilization both metaphorically — as is reflected in their use in myths, religions, and symbolism — and quiet literally: since the ancient past, olive oil has been used for preservation, lighting, medicine, healing, cooking, athletic preparation, cleansing, rituals, trade, and even as a form of currency. The olive tree has been a central pillar of societies, driving economies and creating one of the ancient world’s most enduring markets.
All this began five-odd millennia ago, with the first domestication of the wild olive, Olea europaea subsp. europaea var. sylvestris.
The Six Subspecies of Wild Olive Trees
That was a long name for such a familiar tree; and I’ll explain the scientific nomenclature shortly. Before that, however, it is worth noting that there are actually six different subspecies of olive trees:
All these are wild olive trees, with the exception of Olea europaea subsp. europaea, the only one to have been domesticated. Since its domestication, Olea europaea subsp. europaea has been divided into two varieties: Olea europaea subsp. europaea var. europaea -the “common,” domesticated olive tree — and Olea europaea subsp. europaea var. sylvestris which — its ancestral predecessor.
Thus, all olive trees are of the same genus ( Olea) and species ( Olea europaea). This means they are closely related and can interbreed. The olive tree subspecies describe geographically and genetically distinct tree populations — Olea europaea subsp. europaea, for example, is the form native to the Mediterranean basin. The olive tree variety — which applies to the europaea subspecies — is a naturally occurring subset of trees within a subspecies. Importantly, a variety is not the same as a cultivar (“cultivated variety”): the former describes natural populations, whereas the latter refers to trees selected and maintained by humans for specific desirable traits. A Koroneiki olive tree, therefore, would be classified as: Olea europaea subsp. europaea var. europaea ‘ Koroneiki’.
Figure 1 (from (1, 2)): Above: Olea europaea subsp. europaea var. europaea ‘Koroneiki’. Below: Olea europaea subsp. europaea var. sylvestris.
Wild Olive Oil
Wild olive oils have been produced from each of the first four subspecies mentioned in the previous section (3), although the vast majority of olive oil is produced from the Olea europaea subsp. europaea. Of its two varieties, the wild form (var. sylvestris) accounts for only a tiny fraction of total production. Nearly all olive oil produced in the Mediterranean today comes from one or more of the roughly 1,500 domesticated cultivars derived from the domesticated variety (var. europaea).
Why is wild olive oil so scarce? There are many contributing factors. The primary one is that wild olive trees grow spontaneously in natural habitats, far from human-managed agroecosystems and without any human intervention. Cultivars are selected for their fruit size and oil yield, are planted in organized groves to maximize harvesting efficiency, and irrigated and fertilized to boost production. Wild trees are diametrically opposite: they grow under adverse conditions and in harsh landscapes, and their genetics are tuned for survival — not for producing large quantities of olive oil for humans.
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The wild trees’ differential genetics have several phenotypic manifestations which are related to a lower olive oil yield; for example, their fruits are smaller in size, weigh less than cultivated olives, and have a lower per-unit-mass olive oil content than cultivars (4). Genetic and environmental differences also explain much of the variation in biochemical compounds in wild and cultivated olive oils, which in turn account for differences in their organoleptic properties. For example, genes contributing to high levels of polyphenols such as oleocanthal and oleacein contribute to the wild olive oil’s spicier, more bitter, and fruitier flavour.
Figure 2: Wild Olive Oil by Zoefull.
Distinguishing Wild Trees from Domesticated Trees
Despite the scarcity of wild olive trees, and their random and agriculturally inefficient growth, many producers claim the olive oils they produce come from wild trees. To understand this contradiction, we must first consider the myth of the unattended olive tree. The myth — widely spread among olive-farming circles (and mentioned in Tom Mueller’s Extra Virginity) — claims that, left unattended, any domesticated olive tree cultivar will revert back to its original wild form (i.e. that unattended Olea europaea subsp. europaea var. europaea trees transform into Olea europaea subsp. europaea var. sylvestris). This is of-course not true genetically — though, to the olive farmer’s defence, quiet convincing phenotypically. Indeed, unattended cultivars eventually attain characteristics (e.g. smaller fruit, shrubbiness) that resemble truly wild (var. sylvestris) trees. “Wild” is nonetheless, a common term used by olive farmers to describe both truly wild (var. sylvestris) and feral (i.e., escaped domestic) trees.
Scientifically, olive tree varieties — including wild forms — can be identified using genetic markers. One common approach is the analysis of Simple Sequence Repeats(SSRs), which are short, repetitive DNA motifs found throughout the tree’s nuclear genome. Other approaches make use of modern ‘omics’ technologies, such as whole-genome sequencing. Indeed, it is from such molecular approaches that scientists were able to assert that the wild Olea europaea subsp. europaea var. sylvestris is the ancestral form of the cultivated Olea europaea subsp. europaea var. europaea.
Typically, these molecular procedures involve sampling young leaves and/or small twigs from the trees under investigation, providing enough DNA for the laboratory to assess each tree’s genetic profile. Omics approaches require more sophisticated bioinformatic pipelines, including aligning millions of DNA sequence reads from each sample to a high-quality olive reference genome — whether from cultivated or wild form.
Organic Certification of Wild Olive Trees
A frequent question I get is whether wild olive oil is organic.
Organic is a term that grew to popularity among health-aware consumers, with many food-product brands wearing it proudly and others exploiting it for increased pricing. It has become a label for a natural, biological, pure product.
The certifying procedure usually mandates that an olive produces must meet the following requirements:
- Land and production: The trees must be grown in a clearly defined agricultural plot of land (or κτήμα, as it is called in Greece), owned by a producer. The producer must not have used synthetic chemicals — such as pesticides and fertilizers — on this plot of land for at least two years prior to production.
- Operational requirements: The producer must be maintain, and be able to provide at any moment, detailed documentation on the practise methods they apply to their piece of land.
- Inspection requirements: The land to be certified will undergo an initial and subsequent annual on-site inspections by an accredited body.
Therefore, it is clear organic certification has not been designed for wild, non-farmed trees growing across uncultivated landscapes, without an owner and without an agricultural plot to certify.
One might of course ask the question: “Are these trees organic in the everyday sense?” Yes — by what most people mean when they picture organic products (no pesticides, fertilizers, and other chemicals), these trees are organic. They grow in the most natural way possible, as nature intended them to. Many would even go as far as to call them “ beyond organic.”
References
1) https://worldolivecatalogue.internationaloliveoil.org/en/variety/greece/koroneiki
3) Reyes-Goya C, Santana-Garrido Á, Espinosa-Martín P, Vázquez CM, Mate A. Wild and cultivated olive trees: Nutraceutical insights of extra virgin olive oils in cardiovascular and ocular diseases. Biochim Biophys Acta Mol Basis Dis. 2024 Jan;1870(1):166904. doi: 10.1016/j.bbadis.2023.166904. Epub 2023 Oct 3. PMID: 37793462.
4) Pavlidis DE, Kafentzi MC, Rekoumi K, Koliadima A, Papadelli M, Papadimitriou K, Kapolos J. Turn to the wild: A comprehensive review on the chemical composition of wild olive oil. Food Res Int. 2024 Nov;196:115038. doi: 10.1016/j.foodres.2024.115038. Epub 2024 Sep 10. PMID: 39614480.
Originally published at https://zoefull.com.
